Retaining walls are used to constrain earth embankments from sliding or falling and are commonly constructed from retaining wall blocks. The blocks typically have an interconnecting feature and are commonly stacked in tiers to the desired height to form the retaining wall. The tiers of blocks are often offset with respect to one another to form a retaining wall that is inclined from vertical with each successive upper tier stepped away from the adjacent lower tier.
Various blocks have been proposed for constructing retaining walls. One block is that shown in U.S. Pat. No. 5,161,918 to Hodel (hereinafter the '918 patent), which discloses a block having a hole and pin arrangement for interlocking adjacent tiers of blocks in a set-back relation. The pins are rotatably adjustable to interlock the tiers in a straight configuration or in varying degrees of convex and concave configurations.
Another retaining wall block is that disclosed in U.S. Pat. No. 4,909,010 to Gravier (hereinafter the '010 patent), which discloses a block with a stepped top surface. The stepped top surface provides an interlock area to receive additional blocks thereon to create a retaining wall.
U.S. Pat. No. 5,505,034 to Dueck (hereinafter the '034 patent) discloses a block for forming a retaining wall that includes an internal cavity and protruding knobs having a rounded surface. The rounded knobs are positioned for protruding into the internal cavity of at least one other block in a wall formed from the blocks and are adapted to abut the internal walls of the open cavity to position the block in the retaining wall.
Although the aforementioned patents disclose blocks having features useful for forming a retaining wall, they are not optimal. The hole and pin arrangement of the '918 patent requires the manufacture of pins separate of the blocks which adds to the cost of the retaining wall. Additionally, for each block fitted into the wall, the pins must be set in place and rotated to the correct orientation to create the desired wall configuration.
The interlocking system of the '010 patent, as a result of the outer front edges of an upper block contacting the interlocking step in the top surface of a lower row of blocks, is better suited to the construction of straight retaining walls. When used to construct a curved retaining wall the blocks of the '010 patent contact the lower tier of blocks on their outer bottom edges, which causes a large gap to form between the lower front edge of the block in an upper tier of blocks and the front lip of the blocks in the lower tier. This gap will widen and become excessive as the curved retaining wall is built higher, as the radius of curvature decreases with each successive layer. The '010 patent does mention that the block can be modified to form curved surfaces, but only shows a dotted line configuration and no embodiments are shown in the figures except for the dotted line suggestion.
Forming a curved wall with the single cavity block of the '034 patent requires the installer to break off two frangible extensions, which being a part of the original block detracts from the coverage to weight ratio of the block. A disadvantage of the single cavity block of the '034 patent is that the frangible extensions extend to a line perpendicular to the front face of the bloc, requiring the installer to break off the two frangible extensions when forming a curved wall. Including the frangible extensions decreases the coverage to weight ratio for a portion that eventually will be removed and discarded in the construction of a curved retaining wall, adding to wastage of material. Additionally, the top surface of a block according to the '034 patent is flat, therefore not allowing a block placed on top of a lower tier to be slid between adjacent cavities without first lifting the block to elevate the projecting means above the side walls of the blocks in the lower tier.
The retaining wall block of the present invention includes sharply diverging side walls and wings that extent substantially less than a plane tangent to the front corner and perpendicular to the front face of the block. This block geometry enables construction of either a straight or curved retaining wall without requiring any portion of the blocks to be broken away, thereby decreasing wastage and increasing the coverage to weight ratio of the blocks. The block of the present invention also includes channels formed in the top surface of the blocks, thereby allowing a block in a straight wall to be repositioned without requiring it to be lifted to clear the side walls of the blocks in the lower tier.
The block of the present invention therefore simplifies construction of a retaining wall by decreasing the weight of the block for a given coverage area and by virtue of the channels in the top surface making it easier for the block to be repositioned.
These, and other advantages will be apparent to a person skilled in the art by reading the attached description along with reference to the attached drawings.